Considering that all of these papers are manufactured by Harman Technology, why is there such a large price difference between the fibre-based Ilford VC papers and the Kentmere Fineprint VC paper?

http://www.ag-photographic.co.uk/ilf...ie-fb-43-c.asp

http://www.ag-photographic.co.uk/mgi...gloss-51-c.asp

http://www.ag-photographic.co.uk/mgiv-fb-gloss-47-c.asp

http://www.ag-photographic.co.uk/fin...ibre-135-c.asp